Italy earthquake: NASA radar maps reveal massive damage

NASA radar map showing the massive extent of damage in Amatrice following the 24 August 2016 M=6.2 Italy earthquake. This data, was graciously provided by Dr. Sang-Ho Yun, NASA JPL.

Last week’s M=6.2 Italy earthquake left many parts of the medieval city of Amatrice in ruin. In the old part of the city, most buildings were made of unreinforced masonry, leaving them susceptible to collapse [Guidoboni and Valensise, 2015]. Amatrice was all but destroyed in three large shocks over 19 days in 1703, and so the part of the town that was highly damaged on 24 August 2016 was composed of buildings largely constructed about 300 years ago. In contrast, the newer construction in the east side of the town came through the M=6.2 quake relatively unscathed.

The damage map above includes data provided to Temblor by NASA detailing damage. NASA’s damage assessment comes from ground surface changes analyzed using radar satellite imagery taken before (27 Jan 2016) and after (24 Aug 2016) the earthquake. The images are differenced with a method termed interferometric satellite synthetic aperture radar (InSAR). The image therefore maps changes in the precise locations of buildings, and closely correlates with visual inspection on the ground (For more information about the imaging technique, click here ). The numbers in the figure above correspond to the locations of the images below.

Corso Umberto (Photo: Reuters).One of the main squares in the center of the old part of town (Photo: AP Images).Southern part of Corso Umberto (Photo: The Guardian).San Francesco Church (Photo: La Presse).Viale Francesco Grifoni (Photo: Filippo Monteforte).

Sources:

Dr. Sang-Ho Yun, NASA JPL, Leader of the ARIA program, who graciously provided the damage maps to his colleagues and the public.

Having personally lived in, experienced similar Abruzzo region villages and basic firsthand knowledge of building construction the extent of physical damage from this quake is not surprising ; if you examine Amatrice town layout of in comparison to the satellite data, you will note that the core areas most affected tend to be taller, contiguous structures that are very susceptible to strong lateral & vertical shaking forces, along with the effects of adjoining asymmetric structures of various mass banging into each other, along with the predominantly unreinforced and traditional rubble stone / mortar construction. Interestingly, appears the town’s Campanile ( clock tower ) is still standing which may be clue that it was not affected by adjoining structures and it’s construction was superior.

Ross Stein

Thank you for these very insightful remarks. Your inferences are bolstered by the near-absence of damage in the more modern (eastern) side of Amatrice. In Temblor, we are exploring whether we can factor building proximity into our damage estimates, which would be important for cities lie San Francisco, where buildings of different heights (and therefore natural periods) are in close contact. Rather than sway back in forth in harmony, they would bang into each other. In the 1985, most of Mexico City’s losses were related to this phenomenon.

Joe Scopino

Ross- I’m sure your suggestion would be a useful tool in dense urban areas like SF, however may be difficult to implement due to number of configuration variables including but limited to height, mass, geometry, construction type, soils, etc. Getting back to the Italian quake for moment, many of these old indigenous towns have been around for centuries and heavily subject to tremors & landslides and most are still standing ; I am a native of an Italian hill town in central Abruzzi ( * photo I took of it back in the 1970’s on Google link : http://www.panoramio.com/photo/9720794 ) which fortunately is on the outer eastern fringe of Italy’s high seismic zone. A good source of information on indigenous villages in Italy and other parts of the world are publications by an American Architect / Photographer Norman Carver ( article link here w/ link to his publishing website included : http://www.mlive.com/living/kalamazoo/index.ssf/2011/10/photographer_and_architect_nor.html ). Many of these village structures were founded on stable rock outcrops, and in many cases contiguous structures act to buttress themselves from quake shear forces ; unfortunately the “achilles heel” remains predominantly the old un-reinforced rubble stone construction which has little forgiveness for stress relying on mass / gravity for stability.